1. Data Group D: Environmental Data

A complete environmental description consists of environmental constants, wave and current data. When an environment description has been completed, a new one may be given by repeating data groups Identification of the environment' to `Current parameters' with the appropriate data for the new environment. Up to 10 complete environmental descriptions may be given as input to `INPMOD in one run each identified by an unique identifier given in data group `Identification of the environment'. The minimum data required in one environmental condition is environmental constants (i.e. data groups `Water depth and wave indicator' and `Environment constants' are required).

Note that this data group is dummy for coupled analysis.

1.1. Identification of the environment

1.1.1. Data group identifier, one input line

ENVIronment IDENtification

1.1.2. Describing text. One input line

< TEXT >
  • character(60):

Description of the environment by alphanumerical text. Note: May be empty, but must be present.

1.1.3. Data-set identifier. One input line

IDENV
  • IDENV: character(6): Data set identifier for this environment description. Each environment must have a unique identifier.

1.2. Water depth and wave indicator

1.2.1. Data group identifier, one input line

WATErdepth AND WAVEtype

1.2.2. Water depth and control parameters. One input line

WDEPTH NOIRW NORW NCUSTA NWISTA
  • WDEPTH: real: Water depth \(\mathrm {[L]}\)

  • NOIRW: integer: Number of irregular wave cases, maximum 10

  • NORW: integer: Number of regular wave cases, maximum 10

  • NCUSTA: integer: Number of current states, maximum 10

  • NWISTA: integer, default: 0: Number of wind states, maximum 10

WDEPTH>0. This water depth is defined as a scalar. This parameter is used in calculation of water particle motions.

An environment description can contain up to 10 irregular wave cases and 10 regular wave cases. A uniquely defined environment used in STAMOD or DYNMOD must refer to the actual environment by the identifier IDENV and wave case number.

If a numerically defined spectrum is used, IWASP1=5 in Irregular wave control, the number of irregular wave cases is limited to NOIRW=1.

If a current line (Spatially varying current) is specified, then NCUSTA must be set to the total number of current profiles given.

1.3. Environment constants

1.3.1. Data group identifier, one input line

ENVIronment CONStants

1.3.2. Constants. One input line

AIRDEN WATDEN WAKIVI AIRKIVI
  • AIRDEN: real > 0: Air density \(\mathrm {[M/L^3]}\)

  • WATDEN: real > 0: Water density \(\mathrm {[M/L^3]}\)

  • WAKIVI: real, default: \(\mathrm {1.188\times 10^{-6}}\): Kinematic viscosity of water \(\mathrm {[L^2/T]}\)

  • AIRKIVI: real, default: \(\mathrm {1.516\times 10^{-5}}\): Kinematic viscosity of air \(\mathrm {[L^2/T]}\)

Typical values of AIRDEN and WATDEN are \(\mathrm {[AIRDEN=1.3kg/m^3]}\) and if the units m and kg are used.

1.4. Irregular waves

This data group is given only if NOIRW > 0, and is then repeated NOIRW times.

1.4.1. Data group identifier, one input line

NEW IRREgular SEAState

1.4.2. Irregular wave control data

Irregular wave control
NIRWC IWASP1 IWADR1 IWASP2 IWADR2
  • NIRWC: integer: Irregular wave case number

  • IWASP1: integer: Wave-spectrum type (wind sea)

    • IWASP1=1: Two-parameter Pierson-Moscowitz type spectrum

    • IWASP1=2: One-parameter Pierson-Moscowitz type spectrum

    • IWASP1=3: Jonswap spectrum

    • IWASP1=4: Derbyshire-Scott spectrum

    • IWASP1=5: Numerically defined spectrum

    • IWASP1=6: Ochi spectrum

      • To be used only for SI and modified SI units

    • IWASP1=7: Bretschneider I spectrum

      • To be used only for SI and modified SI units

    • IWASP1=8: Bretschneider II spectrum

      • To be used only for SI and modified SI units

    • IWASP1=9: Three parameter Jonswap spectrum

      • To be used only for SI and modified SI units

    • IWASP1=10: Double peaked spectrum (Torsethaugen)

      • To be used only for SI and modified SI units

  • IWADR1: integer: Wave-direction code (wind sea)

    • IWADR1=0: Unidirectional

    • IWADR1>1: Cosine-spreading function, IWADR1 directions are used.

    • IWADR1=1: Cosine-spreading function, 11 directions are used. IWADR1=1 is thus equivaent to specifying IWADR1=11.

  • IWASP2: integer: Wave-spectrum type (swell)

    • IWASP2=0: No swell spectrum

    • For interpretation of other values, see IWASP1 above

  • IWADR2: integer: Wave-direction code (swell) (dummy if IWASP2=0)

    • IWADR2=0: Unidirectional

    • IWADR2>1: Cosine-spreading function, IWADR2 directions are used.

    • IWADR2=1: Cosine-spreading function, 11 directions are used. IWADR2=1 is thus equivaent to specifying IWADR2=11.

Bretschneider I is based on fetch and wind speed. Bretschneider II is based on wave height and wave period.

For IWADR1 > 0, the directions will be evenly spaced around the average wave propagation direction WADIR1 at intervals of 180/(IWADR1+1) degrees. Specifying an even numbers of directions should be avoided as the average wave propagation direction will not be included in this case. The same applies to IWADR2.

1.4.3. Wave spectrum parameters (wind sea)

Data group identifier, one input line
WAVE SPECtrum WIND
Spectrum parameters

One of (i), (ii), …., (x) is given, depending on the value of the IWASP1 parameter in the data group Irregular wave control data above.

(i) Two-parameter Pierson-Moscowitz (IWASP1=1), one input line.
SIWAHE AVWAPE
  • SIWAHE: real: Significant wave-height, \(\mathrm {H_S}\) \(\mathrm {[L]}\)

  • AVWAPE: real > 0: Zero-crossing wave-period, \(\mathrm {T_Z}\) \(\mathrm {[T]}\)

    1. - \(\mathrm {S_{\eta }(\omega )=A\omega ^{-5}exp[-^B/\omega ^4];0<\omega <\infty}\)

      • \(\mathrm {A=124.2H_S^2/T_Z^4}\) - \(\mathrm {B=496/T_Z^4}\)

The relation between peak period, \(\mathrm {T_p}\) and zero-crossing period is \(\mathrm {T_Z\approx T_p/1.408}\)

(ii) One-parameter Pierson-Moscowitz (IWASP1=2), one input line
SIWAHE
  • SIWAHE: real > 0: Significant wave-height, \(\mathrm {H_S}\) \(\mathrm {[L]}\)

    • \(\mathrm {S_{\eta }(\omega )=A\omega ^{-5}exp[-^B/\omega ^4];0<\omega <\infty}\)

      • \(\mathrm {A=0.0081g^2}\)

      • \(\mathrm {B=3.11/H_S^2}\)

(iii) Jonswap spectrum (IWASP1=3), one input line
PEAKFR ALPHA BETA GAMMA SIGMAA SIGMAB
  • PEAKFR: real > 0: Peak frequency (wp) \(\mathrm {[radians/T]}\)

  • ALPHA: real, default: 0.008: Phillip’s constant

  • BETA: real, default: 1.25: Form parameter

  • GAMMA: real, default: 3.3: Peakedness parameter giving the ratio of the maximum spectral energy to that of the corresponding Pierson- Moscowitz spectrum

    • 0 < GAMMA <= 20

  • SIGMAA: real > 0, default: 0.07: Spectrum width parameter

  • SIGMAB: real > 0, default: 0.09: Spectrum width parameter

  • \(\mathrm {S_{\eta }(\omega )=\alpha g^2\omega ^{-5}exp(-\beta (\frac{\omega _p}{\omega })^4)\times \gamma ^{exp(-\frac{(\omega -\omega _p)^2}{2\sigma ^2\omega ^2_p})}}\)

  • \(\mathrm {\alpha =1.2905H_S^2/T_Z^4}\)

  • \(\mathrm {\beta =1.25}\) for North Sea conditions

  • \(\mathrm {\gamma =}\) \(\begin{cases}\mathrm {1.0;}\quad \mathrm {T_p>=5\sqrt{H_S}}\\\mathrm {exp(5.75-1.15T_p/\sqrt{H_S})}\\\mathrm {5.0;}\quad \mathrm {T_p<3.6\sqrt{H_S}}\end{cases}\)

  • \(\mathrm {\sigma =}\) \(\begin{cases}\mathrm {\sigma _a=0.07}\quad \mathrm {for}\quad \omega \<=\omega _p\\\mathrm {\sigma _b=0.09}\quad \mathrm {for}\quad \omega \<=\omega _p\end{cases}\)

  • \(\mathrm {\omega _p=\frac{2\pi }{T_p}}\) - \(\mathrm {\frac{T_p}{T_Z}=1.407(1-0.287ln\gamma )^{1/4}}\)

(iv) Derbyshire-Scott spectrum (IWASP1=4), one input line
SPEC1 SPEC2 SPEC3 SIWAHE AVWAPE TRUNCL TRUNCU
  • SPEC1: real, default: 0.214: Spectrum parameter, a \(\mathrm {[T/rad]}\)

  • SPEC2: real > 2, default: 0.065: Spectrum parameter, b \(\mathrm {[rad/T]}\)

  • SPEC3: real, default: 0.26: Spectrum parameter, d \(\mathrm {[rad/T]}\)

  • SIWAHE: real: Significant wave height, \(\mathrm {H_S}\) \(\mathrm {[L]}\)

  • AVWAPE: real > 0: Average wave period, \(\mathrm {T}\) \(\mathrm {[T]}\)

  • TRUNCL: real, default: 0.0414: Lower truncation parameter \(\mathrm {[radians/T]}\)

  • TRUNCU: real, default: 10.367: Upper truncation parameter \(\mathrm {[radians/T]}\)

  • \(\mathrm {S_{\eta }(\omega )=\alpha H_S^2exp\sqrt{\frac{(\omega -\omega _p)^2}{b(\omega -\omega _p+d)}}}\) for \(\mathrm {TRUNCL<\omega <TRUNCU}\)

(v) Numerically defined spectrum (IWASP1=5)

Both (v.1) and (v.2) must be given.

(v.1) Number of discrete frequencies, one input line.

NDFRQ1
  • NDFRQ1: integer >= 4: Number of discrete frequencies

(v.2) Spectrum values, NDFRQ input lines. Either:

FRQ DSPDEN
  • FRQ: real: Frequency \(\mathrm {[radians/T]}\)

  • DSPDEN: real: Associated discrete spectral density value \(\mathrm {[L^2T]}\)

The input lines must be given in sequence of increasing frequency values.

(vi) Ochi spectrum (IWASP1=6), one input line.
SIWAHE
  • SIWAHE: real: Significant wave height \(\mathrm {[L]}\)

(vii) Bretschneider spectrum I (IWASP1=7), one input line
FETCH WISPD
  • FETCH: real: Fetch \(\mathrm {[L]}\)

  • WISPD: real: Wind speed \(\mathrm {[L/T]}\)

(viii) Bretschneider spectrum II (IWASP1=8), one input line
SIWAHE SIWAPE
  • SIWAHE: real: Significant wave height \(\mathrm {[L]}\)

  • SIWAPE: real > 0: Significant wave period \(\mathrm {[T]}\)

(ix) Three parameter JONSWAP spectrum (IWASP1=9), one input line.
SIWAHE PEAKPE GAMMA
  • SIWAHE: real: Significant wave height \(\mathrm {[L]}\)

  • PEAKPE: real > 0: Peak period \(\mathrm {[T]}\)

  • GAMMA: real, default: see below: Peakedness parameter giving the ratio of the maximum spectral energy to that of the corresponding Pierson-Moscowitz spectrum

    • 0< GAMMA <= 20

Default value of GAMMA is calculated from SIWAHE and PEAKPE, see (iii) Jonswap spectrum (IWASP1=3):

\(\mathrm {GAMMA=exp[5.75-1.15\times \frac{PEAKPE}{\sqrt{SIWAHE}}]}\)

\(\mathrm {1\<=GAMMA\<=5}\)

Note that use of the three parameter JONSWAP spectrum requires that the SI units m and s be used.

(x) Double peaked JONSWAP spectrum (IWASP1=10) (described by Torsethaugen) , one input line.
SIWAHE PEAKPE
  • SIWAHE: real: Significant wave height \(\mathrm {[L]}\)

  • PEAKPE: real > 0: Peak period \(\mathrm {[T]}\)

Note that use of the double peaked JONSWAP spectrum requires that the SI units m and s be used.

1.4.4. Wave spectrum parameters (swell)

This data group is omitted for IWASP2=0, see Irregular wave control data (no swell present).

Data group identifier, one input line
WAVE SPECtrum SWELl
Spectrum parameters

One of (i), (ii), …, (x) is given, depending on the value of the IWASP2 parameter given in data group Irregular wave control data. The input is identical to input of wind sea spectrum and is therefore not repeated, see Wave spectrum parameters (wind sea).

1.4.5. Direction parameters of waves

Data group identifier, one input line
DIRECTION PARAMETERS

The two input lines below (`Wave direction parameters (wind sea)' and `Wave direction parameters (swell)') must be given in sequence if both are present.

Wave direction parameters (wind sea), one input line
WADR1 EXPO1

If IWADR1 > 0, a cosine directional spreading function is used: \(\mathrm {f(\alpha _i)=\frac{[cos(\alpha _i-WADR1)]^{EXPO1}}{\sum[f(\alpha _j)]}}\) where \(\mathrm {\alpha _i}\) is one of the IWADR1 short-crested wave directions. The sum in the denominator is taken over all IWADR1 directions. The total wind sea energy is thus kept.

Wave direction parameters (swell), one input line

This data group is omitted for IWASP2=0, see Irregular wave control data (no swell present).

WADR2 EXPO2

If IWADR2 > 0, a cosine directional spreading function is used: \(\mathrm {f(\alpha _i)=\frac{[cos(\alpha _i-WADR2)]^{EXPO2}}{\sum[f(\alpha _j)]}}\) where \(\mathrm {\alpha _i}\) is one of the IWADR2 short-crested wave directions. The sum in the denominator is taken over all IWADR2 directions. The total swekk energy is thus kept.

1.5. Regular waves

This data group is given only if NORW > 0.

1.5.1. Data group identifier, one input line

REGULAR WAVE DATA

1.5.2. Regular wave data, NORW input lines

INRWC AMPLIT PERIOD WAVDIR
  • INRWC: integer: Regular wave case number

  • AMPLIT: real: Wave amplitude \(\mathrm {[L]}\)

  • PERIOD: real > 0: Wave period \(\mathrm {[T]}\)

  • WAVDIR: real: Wave propagation direction from the global X-axis \(\mathrm {[deg]}\)

1.6. Current parameters

This data group is given only if NCUSTA > 0, and is then repeated NCUSTA times.

1.6.1. Data group identifier, one input line

May be omitted if no current is present for actual environment.

NEW CURRENT STATE

1.6.2. Current dimension parameter, one input line

ICUSTA NCULEV L_EXT
  • ICUSTA: integer: Current state number

  • NCULEV: integer: Number of current levels

  • L_EXT: integer, default: 0: Flag to indicate if current data is given in this input file, or if it shall be read from an external file.

    • For details on the format of the external file, confer CURMOD User’s Documentation.

    • 0: Data specified on this file

    • 1: Data specified on external file

1 <= NCULEV <= 30. Current states must be given in increasing order, i. e. 1,2, …​, NCUSTA

1.6.3. Current profile, one input line per current level, i.e. NCULEV input lines

This data group is given only if L_EXT = 0
CURLEV CURDIR CURVEL
  • CURLEV: real: Z coordinate of level given in global coordinate system \(\mathrm {[L]}\)

  • CURDIR: real: Current velocity direction at this level. The angle is measured in degrees from the global X-axis counter-clockwise around the global Z-axis. (seen from above)

  • CURVEL: real: Current velocity at this level \(\mathrm {[L/T]}\)

The input lines must be given in sequence of decreasing Z coordinates. Linear interpolation is applied between the levels. Outside the specified range of levels a flat extrapolation is used, i.e. for Z > CURLEV(1) the velocity is set to CURVEL(1) and for Z < CURLEV(NCULEV) the velocity is set to CURVEL(NCULEV)

This current profile may be scaled when applied in static or dynamic analysis.

Z coordinate is zero at mean water level and negative below sea surface.

This data group is given only if L_EXT = 1
CURRFILE
  • CURRFILE: character(120): Name of external file with specified current data

1.7. Spatially varying current

1.7.1. Data group identifier, one input line

NEW CURRENT LINE

1.7.2. Current line control parameters, one input line

ICUSTA NPT
  • ICUSTA: integer: Current state number

  • NPT: integer: Number of current profiles given

The number of current states NCUSTA (see Water depth and control parameters) must be increased by NPT for each current line specified.

Current states must be given in ascending order

1.7.3. Current dimension parameters, one input line

IPT NCULEV XPT YPT
  • IPT: integer: Current profile number. Must be given from 1 to NPT consecutively

  • NCULEV: integer: Number of current levels

    • 1 < NCULEV <= 30

  • XPT: real: Global X- and Y- coordinates

  • YPT: real: For which this current profile is specified

1.7.4. Current profile, one input line per current level, i.e. NCULEV input lines

CURLEV CURDIR CURVEL
  • CURLEV: real: Z coordinate of level given in global coordinate system \(\mathrm {[L]}\)

  • CURDIR: real: Current velocity direction at this level. The angle is measured in degrees from the global X-axis counter-clockwise around the global Z-axis. (seen from above)

  • CURVEL: real: Current velocity at this level \(\mathrm {[L/T]}\)

The input lines must be given in sequence of decreasing Z coordinates. Linear interpolation is applied between the levels. Outside the specified range of levels a flat extrapolation is used, i.e. for Z > CURLEV(1) the velocity is set to CURVEL(1) and for Z < CURLEV(NCULEV) the velocity is set to CURVEL(NCULEV)

This current profile may be scaled when applied in static or dynamic analysis.

Z coordinate is zero at mean water level and negative below sea surface.

1.8. Wind parameters

This data group is given only if NWISTA > 0, and is then repeated NWISTA times.

1.8.1. Data group identifier, one input line

May be omitted if no wind is present for actual environment.

NEW WIND SPECification

1.8.2. Wind case number, one input line

IWISTA
  • IWISTA: integer: Wind case number

1.8.3. Wind type, one input line

IWITYP
  • IWITYP: integer: Wind type

    • IWITYP=10: Stationary uniform wind with shear, values interpolated at grid points

    • IWITYP=11: Fluctuating uniform 2-component wind

    • IWITYP=12: Fluctuating 3-comp. wind read from files (IECWind format)

    • IWITYP=13: Fluctuating 3-comp. wind read from files (TurbSim Bladed style format)

    • IWITYP=14: Stationary uniform wind with shear

The wind types 10 - 14 are intended for wind turbine analyses. However, they may also be applied for other type of analysis.

For the IECWind fluctuating 3-component wind (IWITYP=12), only the fluctuating part of the wind is given in the wind input files. The mean wind speed UMEAN given above is added to the yield the total wind velocity in the longitudinal direction. The input files must conform to the 3-dimensional 3-component wind time series from the rectangular IEC format (See Thomsen, K., 2006. Mann turbulence for the IEC Code Comparison Collaborative (OC3). Risø National Laboratory). More specifically they must include time series of wind velocity in binary format, with a 3-dimensional array having indices in vertical direction running fastest, then indices in lateral direction and indices in longitudinal direction running slowest.

For wind files from NREL’s TurbSim (IWITYP=13), the mean wind speed and shear are included in the binary files. The input files must be generated by TurbSim with WrBLFF=True. Both the .wnd file and .sum file are needed.

1.8.4. Wind type specifications

Stationary uniform wind with shear, values interpolated at grid points (IWITYP=10)

Wind direction, one input line

WIDIR
  • WIDIR: real: Wind propagation direction in global XY-plane \(\mathrm {[deg]}\)

Wind velocity, one input line

UMVEL VMVEL WMVEL
  • UMVEL: real: Longitudinal wind velocity component \(\mathrm {[L/T]}\)

  • VMVEL: real: Lateral wind velocity component \(\mathrm {[L/T]}\)

  • WMVEL: real: Vertical (global Z-axis) wind velocity component \(\mathrm {[L/T]}\)

The parameters UMVEL and VMVEL refer to the direction given by the WIDIR parameter

Number of levels in shear profile, one input line

NZPROF
  • NZPROF: integer: Number of vertical levels for defining the shear profile

Wind velocity profile definition, NZPROF input lines

ZLEV UFACT VFACT WFACT
  • ZLEV: real: Vertical coordinate of profile level \(\mathrm {[L]}\)

  • UFACT: real: Wind speed scaling factor for longitudinal wind velocity

  • VFACT: real: Wind speed scaling factor for the lateral wind velocity

  • WFACT: real: Wind speed scaling factor for the vertical wind velocity

Wind field domain location, one input line

 Z0
  • Z0: real: Z coordinate of the lower edge of the wind field domain \(\mathrm {[L]}\)

Domain size, one input line

NS
  • NZ: integer: Number of grid points in Z- (vertical) direction

Domain resolution, one input line

DLWFZ
  • DLWFZ: real: Domain resolution in the vertical direction \(\mathrm {[L]}\)

Fluctuation uniform 2-component wind read from file (IWITYP=11)

Wind direction, one input line

WIDIR
  • WIDIR: real: Wind propagation direction in global XY-plane \(\mathrm {[deg]}\)

Wind data file name, one input lines

CHWIFI
  • CHWIFI: character(256): Path and filename for import of wind velocity time series. See the SIMO User Manual (`Reading wind time series from file' in `Initialization of time domain simulation' in `Use of DYNMOD') for explanation on file format.

Fluctuating 3-component wind field read from IECWind format file (IWITYP=12)

Mean wind direction, one input line

WIDIR
  • WIDIR: real: Wind propagation direction in global XY-plane \(\mathrm {[deg]}\)

Mean wind velocity, one input line

UMVEL
  • UMVEL: real: Mean wind velocity along WIDIR \(\mathrm {[L/T]}\)

Number of levels in shear profile, one input line

NZPROF
  • NZPROF: integer: Number of vertical levels for defining the shear profile

Wind velocity profile definition, NZPROF input lines

ZLEV UMFACT UFACT VFACT ZFACT
  • ZLEV: real: Vertical coordinate of profile level \(\mathrm {[L]}\)

  • UMFACT: real: Scaling factor for the mean wind velocity

  • UFACT: real: Scaling factor for fluctuating part of the longitudinal wind velocity

  • VFACT: real: Scaling factor for fluctuating part of the lateral wind velocity

  • ZFACT: real: Scaling factor for fluctuating part of the vertical wind velocity

Name of file containing the fluctuating longitudinal wind time series, one input line

CHWFU
  • CHWFU: character(256): Path and filename for the fluctuating U-component wind time series

Name of file containing the fluctuating lateral wind time series, one input line

CHWFV
  • CHWFV: character(256): Path and filename for the fluctuating V-component wind time series

Name of file containing the fluctuating vertical wind time series, one input line

CHWFW
  • CHWFW: character(256): Path and filename for the fluctuating Z-component wind time series

Wind field domain location, one input line

X0LL Y0LL Z0LL
  • X0LL: real: X-coordinate of the lower left corner of the upstream border of the wind field domain \(\mathrm {[L]}\)

  • Y0LL: real: Y-coordinate of the lower left corner of the wind field domain \(\mathrm {[L]}\)

  • Z0LL: real: Z-coordinate of the lower left corner of the wind field domain\(\mathrm {[L]}\)

These three coordinates defines the lower left corner of the wind field domain, which is defined as a rectangular cuboid. The coordinates refers to a coordinate system centred at the global origin, with the x-axis (longitudinal direction) pointing in the down-stream mean wind speed direction and the z-axis coincident with the global z-axis.

Domain size, one input line

NX NY NZ
  • NX: integer: Number of grid points in X- (longitudinal) direction \(\mathrm {[L]}\)

  • NY: integer: Number of grid points in Y- (lateral) direction \(\mathrm {[L]}\)

  • NZ: integer: Number of grid points in Z- (vertical) direction\(\mathrm {[L]}\)

Field size, one input line

LWFX LWFY LWFZ
  • LWFX: real: Field size in X- (longitudinal) direction

  • LWFY: real: Field size in Y- (lateral) direction

  • LWFZ: real: Field size in Z- (vertical) direction

Buffer size, one input line

NSLICE
  • NSLICE: integer, default: 800: Buffer size: Number of wind crossectional planes (Slices) in memory

um dtumann
Figure 1. The turbulence wind box. The lower left corner is shown with a red dot, and the center of the wind box is located at the green point.
Fluctuating 3-component wind field read from TurbSim file (IWITYP=13)

The wind field domain- and field size are extracted from the TurbSim .sum file.

The wind field domain location in the global coordinate system is not given explicitly by the user. The vertical position of the wind field center is the same as in TurbSim; i.e. taken as the hub height given on the turbsim .sum file.

Horizontally, the wind field is positioned around the global origin, but with a half grid width downwind of the origin. Since the TurbSim wind is non-periodic, this is necessary to ensure that the entire turbine lies in the same part of the wind field at the start of the simulation. The wind at the global origin will thus not start at the first slice

The wind field must be large enough to ensure that the whole structure is within the wind field during the entire simulation. As the TurbSim wind field is nonperiodic, the beginning and end of the wind field will not fit together.

Mean wind direction, one input line

WIDIR
  • WIDIR: real: Wind propagation direction in global XY-plane \(\mathrm {[deg]}\)

Name of binary (.wnd) file containing the TurbSim fluctuating wind time series, one input line

CHWFTW
.....

* `CHWFTW: character(256)`: Path and filename for the binary TurbSim
(.wnd) file

Name of the summary (.sum) file from TurbSim, one input line
...
CHWFTS
  • CHWFTS: character(256): Path and filename for the summary TurbSim (.sum) file

Buffer size, one input line

NSLICE
  • NSLICE: integer, default: 800: Buffer size: Number of wind crossectional planes (Slices) in memory

Note: Since TurbSim files are not periodic, time series are shifted by 1/2 Grid Width. The number of slices in memory must be greater than (Grid Width/MeanWindSpeed/WindFileTimeStep).

um turbsim
Figure 2. Example of grid and rotor placements in Turbsim: the circles pictured here are the rotor diameters assumed by TurbSim. The actual rotor diameter(s) will be smaller than in the figures
Stationary uniform wind with shear (IWITYP=14)

Wind direction, velocity and shear profile type, one input line

WIDIR UMVEL WMVEL CH_SHEAR
  • WIDIR: real: Wind propagation direction in global XY-plane \(\mathrm {[deg]}\)

  • UMVEL: real: Longitudinal wind velocity component \(\mathrm {[L/T]}\)

  • WMVEL: real: Vertical (global Z-axis) wind velocity component \(\mathrm {[L/T]}\)

  • CH_SHEAR: character(4): Shear profile type

    • NONE - No shear profile

    • POWR - Power shear profile

    • LOGA - Logarithmic shear profile

UMVEL is the wind velocity in the direction WIDIR.

Poser shear profile input, one input line, only given if CH_SHEAR = POWR

ZREF ALPHA
  • ZREF: real: Reference height \(\mathrm {[L]}\)

  • ALPHA: real: Wind shear exponent \(\mathrm {[-]}\)

Logarithmic shear profile input, one input line, only given if CH_SHEAR = LOGA

ZREF Z0
  • ZREF: real: Reference height \(\mathrm {[L]}\)

  • Z0: real: Roughness length \(\mathrm {[L]}\)